U.S. patent number 10,968,576 [Application Number 16/426,479] was granted by the patent office on 2021-04-06 for self-propelled construction machine and method for working ground pavements.
This patent grant is currently assigned to Wirtgen GmbH. The grantee listed for this patent is Wirtgen GmbH. Invention is credited to Markus Bach, Christian Berning, Axel Mahlberg, Stefan Wagner.
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United States Patent |
10,968,576 |
Wagner , et al. |
April 6, 2021 |
Self-propelled construction machine and method for working ground
pavements
Abstract
In a self-propelled construction machine (1), in particular road
milling machine, recycler, stabilizer or surface miner, comprising
a machine frame (4), at least two travelling devices (2), at least
one hydraulic drive system (50) for driving at least two travelling
devices (2), at least one working device, in particular a milling
drum (6), for working the ground pavement (3), it is provided for
the following features to be achieved: a detection device (44, 60,
62) is provided which detects fluctuations in the longitudinal
speed (v.sub.act) of the construction machine (1) during movement
of the construction machine (1), wherein a control unit (38)
controls the hydraulic drive system (50) as a function of the
detected fluctuations in such a fashion that the drive speed
(v.sub.drive) for driving the travelling devices (2) specified by
means of the hydraulic drive system (50) is continuously adjusted
so that the detected fluctuations are reduced or compensated
for.
Inventors: |
Wagner; Stefan (Bad Honnef,
DE), Bach; Markus (Bonn, DE), Berning;
Christian (Zulpich, DE), Mahlberg; Axel (Hennef,
DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
Wirtgen GmbH |
Windhagen |
N/A |
DE |
|
|
Assignee: |
Wirtgen GmbH (N/A)
|
Family
ID: |
1000005468710 |
Appl.
No.: |
16/426,479 |
Filed: |
May 30, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
|
US 20190390417 A1 |
Dec 26, 2019 |
|
Foreign Application Priority Data
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|
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Jun 22, 2018 [DE] |
|
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10 2018 210 253.8 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E21C
47/00 (20130101); E01C 23/065 (20130101); E01C
23/088 (20130101) |
Current International
Class: |
E01C
23/00 (20060101); E01C 23/088 (20060101); E01C
23/06 (20060101); E21C 47/00 (20060101) |
Field of
Search: |
;404/72,75,84.05-84.5,96-101,117,118,133.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2644775 |
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Oct 2013 |
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EP |
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03064770 |
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Aug 2003 |
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WO |
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Other References
European Search Report for corresponding EP 19 16 6117, dated Jun.
17, 2019, 4 pages (not prior art). cited by applicant.
|
Primary Examiner: Addie; Raymond W
Attorney, Agent or Firm: Beavers; Lucian Wayne Montle; Gary
L. Patterson Intellectual Property Law, PC
Claims
What is claimed is:
1. A self-propelled construction machine for working ground
pavements, the self-propelled construction machine comprising: at
least two travelling devices supporting a machine frame; at least
one hydraulic drive system configured to drive the at least two
travelling devices at a specified drive speed; a detection device
configured to detect fluctuations in a longitudinal speed of the
construction machine during movement of the construction machine,
wherein the fluctuations in the longitudinal speed of the
construction machine are detectable as a vibration by the detection
device; and a control unit configured to control the hydraulic
drive system to continuously adjust the drive speed as a function
of the detected fluctuations.
2. The self-propelled construction machine of claim 1, wherein said
vibration exhibits an essentially fixed frequency.
3. The self-propelled construction machine of claim 1, wherein the
detection device is configured to detect fluctuations in the
longitudinal speed as a fluctuation in one or more of: the
longitudinal speed around a set speed on the travelling devices;
the longitudinal speed around a set speed on the machine frame; the
volumetric flow rate; and the pressure of the hydraulic drive
system.
4. The self-propelled construction machine of claim 3, wherein the
detection device comprises one or more of: a pick-up sensor for
measuring the speed changes; an accelerometer for measuring the
speed changes; and a measuring device for measuring the
fluctuations in pressure or the volumetric flow rate in the
hydraulic drive system.
5. A method for working ground pavements via a working device of a
construction machine that is self-propelled by means of travelling
devices, in which the travelling devices are driven by a hydraulic
drive system at a specified drive speed, the method comprising:
detecting fluctuations in a longitudinal speed of the construction
machine during movement of the construction machine, wherein the
fluctuations in the longitudinal speed of the construction machine
are detected as vibrations; and continuously adjusting the drive
speed as a function of the detected fluctuations.
6. The method of claim 5, wherein the fluctuations in the
longitudinal speed of the construction machine are detected as
vibrations exhibiting an essentially fixed frequency.
7. The method of claim 5, wherein the specified drive speed is
changed periodically to generate a counter-vibration which reduces
or compensates for the detected fluctuations.
8. The method of claim 7, wherein a frequency of the
counter-vibration is adjusted to the frequency of the detected
vibration and is phase-shifted to the same.
9. The method of claim 8, wherein the frequency of the
counter-vibration is phase-shifted opposite in phase to the
frequency of the detected vibration.
10. A self-propelled construction machine for working ground
pavements, the self-propelled construction machine comprising: at
least two travelling devices supporting a machine frame; a
hydraulic drive system comprising at least one hydraulic pump
coupled to at least one hydraulic motor and configured to drive
each of the at least two travelling devices at a specified drive
speed; a detection device configured to detect fluctuations in a
longitudinal speed of the construction machine during movement of
the construction machine as a fluctuation in a volumetric flow rate
and/or pressure of the hydraulic drive system as measured at the
hydraulic pump; and a control unit configured to control the
hydraulic drive system to continuously adjust the drive speed as a
function of the detected fluctuations.
11. The self-propelled construction machine of claim 10, wherein
the displacement capacity of the at least one hydraulic motor is
adjustable to effect a periodical change in the specified drive
speed.
12. The self-propelled construction machine of claim 10, wherein
the control unit is configured to control one or more of the
volumetric flow rate and the pressure in the hydraulic drive system
to effect a periodical change in the specified drive speed.
13. The self-propelled construction machine of claim 10, wherein
the detection device comprises one or more of: a pick-up sensor for
measuring the speed changes; an accelerometer for measuring the
speed changes; and a measuring device for measuring the
fluctuations in pressure or the volumetric flow rate in the
hydraulic drive system.
14. The self-propelled construction machine of claim 10, wherein
the fluctuations in the longitudinal speed of the construction
machine are detectable as a vibration by the detection device.
15. The self-propelled construction machine of claim 14, wherein
the control unit is configured to control the hydraulic drive
system such that the drive speed is continuously adjusted only when
the detected vibration exceeds a predefined amplitude.
16. The self-propelled construction machine of claim 14, wherein
said vibration exhibits an essentially fixed frequency.
17. The self-propelled construction machine of claim 10, wherein
the control unit is configured to control the hydraulic drive
system such that the specified drive speed is changed periodically
to generate a counter-vibration which reduces or compensates for
the detected fluctuations.
18. The self-propelled construction machine of claim 17, wherein
the control unit is configured to control the hydraulic drive
system such that the amplitude of the counter-vibration is adjusted
to the amplitude of the detected vibration.
19. The self-propelled construction machine of claim 17, wherein
the control unit is configured to control the hydraulic drive
system such that the frequency of the counter-vibration is adjusted
to the frequency of a detected vibration and is phase-shifted to
the same.
20. The self-propelled construction machine of claim 19, wherein
the frequency of the counter-vibration is phase-shifted opposite in
phase to the frequency of the detected vibration.
Description
CROSS-REFERENCES TO RELATED APPLICATIONS
This application claims benefit of German Patent Application No. 10
2018 210 253.8, filed Jun. 22, 2018, and which is hereby
incorporated by reference.
FIELD OF THE DISCLOSURE
The invention relates to a self-propelled construction machine as
claimed, as well as to a method for working ground pavements.
BACKGROUND
Self-propelled construction machines are known, in particular road
milling machines, recyclers, stabilizers or surface miners
comprising a machine frame, travelling devices, at least one
hydraulic drive system for driving the travelling devices, and at
least one working device, in particular a milling drum for working
the ground surface.
The road milling machines can be used, for example, to remove
existing ground pavements of roads. Recyclers can be used to
rehabilitate existing ground pavements. The stabilizers serve the
purpose of preparing the sub grade for road construction. Surface
miners can be used to mine coal and rock.
Experience has shown, however, that vibrations may occur during the
operation of the construction machines caused by, for example, a
non-smooth operation of the working device. This may lead to an
excitation of vibrations in the entire construction machine to the
point of the machine rocking, in particular when the vibrations are
in the range of the machine's resonant frequency. According to
prior art, such rocking of the machine is prevented by the machine
operator changing the speed of the construction machine and driving
more slowly. This has the disadvantage, however, that the machine
cannot be operated or moved at the desired speed, and that, as a
consequence, the construction machine is not optimally
utilized.
BRIEF SUMMARY
It is an object of the present invention to create a construction
machine and a method for working ground pavements in which rocking
of the construction machine is avoided or optimized operation of
the construction machine is made possible, respectively.
The invention advantageously provides for a detection device to be
provided which detects fluctuations in the longitudinal speed of
the construction machine during movement of the construction
machine, wherein a control unit controls the hydraulic drive system
as a function of the detected fluctuations in such a fashion that
the drive speed for driving the travelling devices specified by
means of the hydraulic drive system is continuously adjusted so
that the detected fluctuations are reduced or compensated for.
The present invention has the advantage that the fluctuations of
the construction machine are avoided or reduced, respectively, so
that rocking is effectively prevented. At the same time, the
average longitudinal speed of the construction machine may
advantageously remain the same. It is therefore no longer necessary
to reduce the set speed of the construction machine, and the
construction machine may be operated at the desired set speed.
In the present invention, preferably at least two travelling
devices are driven. It is, however, also possible for only two
travelling devices to be driven and further non-driven travelling
devices to be additionally provided.
In the present invention, it must be differentiated between the
longitudinal speed of the construction machine, the set speed, and
the specified drive speed. The longitudinal speed is the actual
speed of the construction machine. The set speed is the speed which
the operator of the construction machine can set on the operating
unit. It must be distinguished from the specified drive speed in
the hydraulic drive system. This is the drive speed specified by
the control unit. The longitudinal speed of the construction
machine is a superimposition of the specified drive speed and
influencing factors of the machine or the environment. The
specified drive speed may be superimposed by fluctuations which are
caused, for example, by a non-smooth operation of the working
device. The specified drive speed is the speed that would ensue in
the case of given operating parameters of the hydraulic drive
system and without any influencing factors.
The fluctuations in the longitudinal speed of the construction
machine may be detectable as a vibration by means of the detection
device. The detectable vibration preferably exhibits an essentially
fixed frequency. Particularly disturbing fluctuations are generated
by vibrations which hit the resonant frequency of the machine so
that rocking of the machine occurs.
The resonant frequency of the machine depends on different
operating variables, such as the current weight (again depending,
inter alia, on the amount of fuel and water present in tanks) and
other factors. Said frequency is therefore variable and cannot
therefore be generally determined for a machine.
The fluctuations in the longitudinal speed have an effect on the
body, on the one hand, in that perceptible "rocking movements"
occur; on the other hand, however, the fluctuation also has an
effect on the hydraulic drive system. The movements of the machine
are transferred back to the hydraulic circuit via the
ground-engaging units and the hydraulic motors, and may there also
be detected as fluctuations in the pressure or in the volumetric
flow rate, respectively.
The control unit may control the hydraulic drive system in such a
fashion that the specified drive speed is changed periodically to
generate a counter-vibration which reduces or compensates for the
detected fluctuations.
In this way, the speed set by the operator of the construction
machine does not have to be changed to prevent the unwelcome
fluctuation of the construction machine.
The control unit may control the hydraulic drive system in such a
fashion that the frequency of the counter-vibration is adjusted to
the frequency of the detected vibration and is phase-shifted to the
same. The phase shift may also be adjusted continuously.
The control unit may control the hydraulic drive system in such a
fashion that the frequency of the counter-vibration is opposite in
phase to the frequency of the detected vibration.
The control unit may control the hydraulic drive system in such a
fashion that the amplitude of the counter-vibration is adjusted to
the amplitude of the detected vibration.
Through the adjustment to the frequency and to the amplitude of the
detected vibration, the unwelcome detected vibration may be
particularly effectively reduced or compensated for.
The hydraulic drive system may comprise at least one hydraulic pump
and at least one hydraulic motor. Furthermore, the hydraulic drive
system may also comprise lines and additional elements such as, for
example, pressure storage reservoirs.
The at least one hydraulic pump may be an axial piston pump. The
hydraulic motor may likewise be an axial piston motor.
The control unit may control the volumetric flow rate and/or the
pressure in the hydraulic drive system so as to effect a periodical
change in the specified drive speed.
The volumetric flow rate and/or the pressure in the hydraulic drive
system may be controllable by means of the hydraulic pump for
adjusting the specified drive speed.
The displacement capacity of the hydraulic motor may likewise be
adjustable so as to effect a periodical change in the specified
drive speed.
The control unit may control the hydraulic drive system in such a
fashion that the drive speed for driving the travelling devices
specified by means of the hydraulic drive system is continuously
adjusted only when the detected vibration exceeds a predefined
amplitude.
In this way, the fluctuations that are particularly unpleasant for
the machine operator, in which rocking of the machine occurs, are
compensated for or reduced first.
The detection device may detect fluctuations in the longitudinal
speed as fluctuations in the longitudinal speed around the set
speed. The detection device may detect the fluctuations on the
travelling devices or on the machine frame and/or as a fluctuation
in the volumetric flow rate and/or as a fluctuation in the pressure
of the hydraulic drive system. During rocking of the construction
machine, tilting back and forth of the construction machine may
also occur. Vertical fluctuations may therefore also be measured
which allow a conclusion to be drawn as to the fluctuations in
longitudinal speed.
The detection device may comprise a pick-up sensor and/or an
accelerometer and/or a measuring device for measuring the
fluctuations in pressure in the hydraulic drive system. An
accelerometer measures the changes in speed, which enables the
fluctuations in the longitudinal speed to be determined.
Furthermore, changes in the volumetric flow rate of the hydraulic
fluid in the hydraulic system, for example, may be measured with an
appropriate sensor.
According to the present invention, a method for working ground
pavements may likewise be provided, comprising a construction
machine self-propelled by means of travelling devices, in
particular road milling machine, recycler, stabilizer or surface
miner, in which the travelling devices are driven by a hydraulic
drive system, wherein a working device works the ground pavement.
In this context, it may in particular be provided that fluctuations
in the longitudinal speed of the construction machine are detected
during movement of the construction machine, and the drive speed
specified by the hydraulic drive system for the travelling devices
is continuously adjusted as a function of the detected fluctuation
so that the detected fluctuations of the construction machine are
reduced or compensated for.
The fluctuations in the longitudinal speed of the construction
machine may be detected as vibrations with an essentially fixed
frequency.
The specified drive speed may be changed periodically to generate a
counter-vibration which reduces or compensates for the detected
fluctuations.
The frequency of the counter-vibration may be adjusted to the
frequency of the detected vibration and may be phase-shifted to the
same.
The frequency of the counter-vibration may be adjusted in such a
fashion that it is opposite in phase to the frequency of the
detected vibration.
According to the present invention, it is decisive that the
specified drive speed does not change in its average during the
adjustment but merely vibrates around the desired set travel
speed.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
Hereinafter, embodiments of the invention are illustrated in more
detail with reference to the drawings.
FIG. 1 shows schematically a self-propelled construction machine in
side view,
FIG. 2 shows schematically drive trains of the construction
machine,
FIG. 3 shows schematically the progression of the detected
longitudinal speed,
FIG. 4 shows schematically the progression of the detected
longitudinal speed and the progression of the drive speed specified
by means of the hydraulic drive system.
DETAILED DESCRIPTION
FIG. 1 shows a construction machine 1. The construction machine may
be a milling machine, in particular a road milling machine, a
recycler or stabilizer, or a surface miner. The construction
machine depicted in FIG. 1 has the form of a road milling machine.
The construction machine 1 may, however, also be any other
construction machine comprising, as a minimum, a hydraulic drive
system and a working device. The depicted construction machine 1
comprises travelling devices 2 which support a machine frame 4. The
travelling devices 2 may be tracked ground-engaging units or
wheels. A working device, preferably a milling drum 6 for working
the ground pavement 3, is mounted on the machine frame 4. To work
the ground pavement 3, the milling drum 6 may comprise non-depicted
milling tools on the shell surface of the milling drum 6. A milling
drum housing 5 is arranged around the milling drum 6. The
construction machine furthermore preferably comprises a conveying
device 46 for transporting away the milling material.
The travelling devices 2 may be connected to the machine frame 4
via lifting columns 48. The machine frame 4 may be adjustable in
height by means of the lifting columns 48. As a result, the milling
drum 6 may also be adjusted in height. Alternatively or
additionally, the milling drum 6 may, in turn, be mounted in a
movable, in particular height-adjustable fashion relative to the
machine frame 4.
FIG. 2 shows a drive train of the construction machine 1. A first
drive train I serves the purpose of transmitting the driving power
to the travelling devices 2, while a second drive train II serves
the purpose of transmitting the driving power to the milling drum
6.
A drive unit 10 is depicted in FIG. 2. Said drive unit 10 may
preferably comprise a combustion engine. Said combustion engine may
in particular be a diesel engine. The drive unit may be provided,
via an elastomer coupling 20, with a pump transfer gearbox 16 for
driving the first drive train I for driving a hydraulic drive
system 50 for driving the travelling devices 2.
In the second drive train II for driving the milling drum 6, a
clutch 14 is provided between the drive unit 10 and the milling
drum 6. Said clutch 14 is a device for switching the torque.
A traction mechanism 12 for the mechanical drive of the milling
drum 6 is arranged between the clutch 14 and the milling drum 6.
The traction mechanism 12 comprises a drive element 11 which is
coupled, in a torsionally rigid fashion, to the driven shaft 22 of
the drive unit 10. The traction mechanism 12 furthermore comprises
a driven element 13 which is coupled, in a torsionally rigid
fashion, to the drive shaft 15 of the milling drum 6. A gearbox, in
particular a planetary gearbox 24, may additionally be arranged
between the drive shaft 15 and the milling drum 6.
The traction mechanism 12 is preferably a belt drive, wherein the
drive elements and driven elements consist of belt pulleys 11 and
13, with one or a plurality of drive belts 30 revolving over said
belt pulleys 11 and 13. Alternatively, the traction mechanism 12
may also consist of a chain drive, wherein the drive elements and
driven elements then consist of sprockets. In principle, the
working device may also be hydraulically or electrically
driven.
In the first drive train I for driving the hydraulic drive system,
the pump transfer gearbox 16 comprises at least one hydraulic pump
32. The at least one hydraulic pump 32 may in turn be connected,
via hydraulic lines 36, to at least one or, as in the embodiment
depicted, a plurality of hydraulic motors 34. The hydraulic motors
34 drive one each travelling device 2, depicted only schematically
in FIG. 2.
Due to the hydraulic drive system, the advance speed of the
construction machine may, in principle, be controlled independently
of the speed of revolution of the drive engine.
During the operation of a construction machine, fluctuations may
occur in the longitudinal speed of the construction machine. Said
fluctuations may be detected by means of a detection device 44. A
control unit 38 may control the hydraulic drive system 50 as a
function of the detected fluctuations in such a fashion that the
drive speed for driving the travelling devices 2 specified by means
of the hydraulic drive system 50 is continuously adjusted so that
the detected fluctuations are reduced or compensated for. That the
control unit 38 controls the hydraulic drive system 50 via the pump
32 is depicted by means of the dashed line 40. The measured values
of the detection device 44 may be transmitted to the control unit
38. This is also depicted by means of a dashed line 45. The term to
control is to be understood to mean that the detection unit 44
records a measured value at least once, and the control unit 38
controls the hydraulic drive system 50 as a function of the
detected fluctuations. It is to also be included, however, that the
detection device records measured values a plurality of times, and
the control device 38 controls the hydraulic drive system 50 as a
function of the detected fluctuations. A feedback in the sense of a
closed-loop control is therefore to also be included in the present
term to control.
The detection device 44 may detect the fluctuations in the
longitudinal speed as a fluctuation in the longitudinal speed
around the set speed. The detection device 44 may detect the
fluctuations on the travelling devices 2 or on the machine frame
and/or as a fluctuation in the volumetric flow rate and/or as a
fluctuation in the pressure of the hydraulic drive system.
In the embodiment depicted, the detection device 44 detects the
fluctuations in the volumetric flow rate and/or the fluctuations in
the pressure in the hydraulic drive system 50. The detection device
44 may measure the fluctuations at any position of the drive system
50, such as the hydraulic pump 32 or the hydraulic lines 36. This
is also depicted by means of dashed lines 41. The control unit 38
may be part of the machine control system of the construction
machine 1. The control unit 38 may, however, also be designed
separately.
FIG. 3 shows the longitudinal speed v.sub.act over time. The
depicted detected longitudinal speed v.sub.act exhibits
fluctuations which fluctuate around a set speed v.sub.set. The set
speed v.sub.set is the speed which the driver can set on an
operating unit. The detected longitudinal speed is termed
v.sub.act. The detected fluctuations are, as depicted, a vibration
with a fixed frequency f. Such rocking of the construction machine
frequently occurs when vibrations occur on the construction machine
which hit a resonant frequency of the construction machine. In the
prior art, said fluctuations could be counteracted only by reducing
the set speed v.sub.set in order to reduce the vibrations which
cause the machine to rock. This has the disadvantage, however, that
the construction machine is moved more slowly altogether than would
generally be possible due to the available machine power.
In the present invention, however, the fluctuation is detected by
means of a detection device 44. The control device 38 controls the
hydraulic drive system in such a fashion that the drive speed
v.sub.drive for driving the travelling device 2 specified by means
of the hydraulic drive system is continuously adjusted so that the
detected fluctuations are reduced or compensated for. This is
depicted in FIG. 4. The detected speed v.sub.act (solid line) is
depicted. Said detected speed fluctuates around a speed v.sub.set
set by the machine operator. The control unit now controls the
hydraulic drive system in such a fashion that the specified drive
speed v.sub.drive (dotted line) is changed in such a fashion that
the fluctuations are reduced or compensated for, respectively. This
is also apparent in FIG. 4. The specified drive speed v.sub.drive
is a counter-vibration to the detected fluctuation. As a result,
the detected fluctuations reduce over time. The specified drive
speed v.sub.drive is also adjusted so that, in the end, the
detected fluctuation of the construction machine reduces to such an
extent that the longitudinal speed of the construction machine
nearly aligns itself to the specified speed v.sub.set.
It is apparent in FIG. 4 that the control unit 38 controls the
hydraulic drive system in such a fashion that the specified drive
speed v.sub.drive is changed periodically in order to generate a
counter-vibration which reduces or compensates for the detected
fluctuations. In the process, the frequency of the
counter-vibration is adjusted to the frequency of the detected
vibration and is phase-shifted to the same. It is particularly
preferred for the frequency of the counter-vibration to be opposite
in phase to the frequency of the detected vibration. Likewise, the
amplitude of the counter-vibration is preferably adjusted to the
amplitude of the detected vibration. In this process, the amplitude
of the detected vibrations is equivalent, for example, to the
maximum deviation of the detected longitudinal speed v.sub.act from
the set speed v.sub.set, whilst the amplitude of the
counter-vibration is equivalent, for example, to the maximum
deviation of the specified drive speed v.sub.drive from the set
speed v.sub.set.
The control unit 38 may adjust the drive speed in the hydraulic
drive system 50 by adjusting the volumetric flow rate and/or the
pressure of the hydraulic drive system by means of the hydraulic
pump 32. Alternatively, the control unit 38 may also adjust the
drive speed in the hydraulic drive system 50 by adjusting the
volumetric flow rate and/or the pressure of the hydraulic drive
system in a position other than the hydraulic pump 32. This may be
effected, for example, by means of an additional, non-depicted,
hydraulic actuator.
The displacement capacity of the hydraulic motors 34 may
alternatively also be adjusted so as to effect a periodical change
in the specified drive speed.
It may be provided for the control unit 38 to continuously adjust
the specified drive speed v.sub.drive only when the detected
fluctuation v.sub.act exceeds a predefined amplitude.
In this way, the construction machine may be moved at any desired
speed v.sub.set and, in contrast to the prior art, as a result of
not having to reduce the specified speed v.sub.set, the
construction machine may therefore also be operated at a higher or
at the optimum speed, respectively.
Additional or alternative detection devices are depicted in the
construction machine according to FIG. 1. A detection device 60
designed as an accelerometer, and a detection device 62 designed as
a pick-up sensor are depicted. Said detection devices may be used,
alternatively or additionally, to reliably detect fluctuations in
the longitudinal speed of the construction machine. Said detection
devices may, however, also be omitted.
* * * * *